In computer systems, functional devices such as disc drives and disc drive controllers in a host computer system are typically connected by transceivers to a transmission line and various connectors that serve as a serial bus. The transmission line, which can be copper conductors or glass fibers, typically has discontinuities at connectors and is not ideal. In the case of copper conductors, there are often impedance discontinuities at connectors and the characteristic impedance of the serial bus typically does not match the impedances at the transceivers. The physical layer characteristics of the data is distorted by impedance discontinuities and mismatch. Performance of the serial bus will vary depending on the uncontrolled length, routing and connectors of the transmission line, leading to reduced bus speed or increased error rates.
A method and apparatus are needed to control and correct the quality of physical layer properties, such as amplitude and frequency rolloff, in such non-ideal arrangements of serial buses. Embodiments of the present invention provide solutions to these and other problems, and offer other advantages over the prior art.